1. Field of the Invention
The present invention relates to systems for the fabrication of wooden trusses and, more particularly, to a receiving arm used to catch trusses and set trusses as part of their transfer between adjacent truss fabrication assembly lines.
2. Description of the Prior Art
A method for fabricating wooden trusses which has been well known for many years involves having the butt joints of each truss secured with unitized toothed metal fasteners or connectors. One such system for the mass fabrication of wooden trusses uses jigs to position the truss members in place on working tables forming a first assembly area. Unitized fasteners are placed on either side of the butt joints and the truss members tacked together by pressing the fasteners into the truss members using a gantry pinch roller. Once tacked, the trusses are laterally transferred to a second conveyor area by a plurality of spaced apart receiving arms. The trusses are then conveyed to a stationary truss pinch roller via conveyor rollers for final pressing of the unitized fasteners so as to firmly embed the fasteners within the butt joints.
Because the trusses are often quite large, they are supported by three or more spaced apart receiving arms. It is conventional that the receiving arms are pivotally mounted to their supports and actuated by pneumatic pistons along arcuate paths dictated by the length of their pivot arms. Ideally, the receiving arms are actuated in unison, however sometimes the receiving arms fail to move in concert with one another. When this happens a portion of the truss being conveyed can slip or be lifted relative to other portions, with the result that the truss is twisted and the securement of the butt joints compromised.